10. Laboratory Evaluation of Fibrinolysis

8/19/2019 10. Laboratory Evaluation of Fibrinolysis

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LaboratoryEvaluation ofFibrinolysisDonna Therese M. Taguinod, RMT, MPH


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Laboratory Tests to Evaluate

Fibrinolysis:1. Whole blood clot lysis time

2. Protamine sulfate dilution test

3. Ethanol gelation test

4. Latex FDP test

5. Latex D-Dimer assay


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Whole Blood Clot Lysis Time

Whole blood (No Anticoagulant)should remain clotted and should notshow significant lysis for 48 hours at

37°C

Positive in severe fibrinolysis


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Euglobulin Lysis Time:

Is used as a screening test forfibrinolytic activity.

The euglobulin fraction of plasma

consists of Fibrinogen, plasminogen,and fibrinolytic activators

The euglobulin fraction is precipitatedwith 1% acetic acid and resuspended

in a borate solution. Euglobulins areclotted by the addition of thrombin (5units/mL). The resulting clot isincubated (37C) and the time of lysis is

obtained.


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Euglobulin Lysis Time:

The clot should remain intact for 2-4hours

Interpretation:

Clot lysis in < 2hours is indicative ofabnormal fibrinolytic activity anddecrease in fibrinogen

A prolonged time > 4 hours is

caused by a decrease inplasminogen or activator.

Note: It does not detect FDPs


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Protamine Sulfate Dilution Test

When protamine is added in plasma, itdisplaces the secondary (smaller)degradation products from fibrinmonomer and primary (larger) FDP will

polymerize spontaneously(paracoagulation)

Normally, no gel formation

(+) result : gel formation = DIC,pulmonary embolism, thrombolytictherapy


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Ethanol Gelation Test

Less sensitive but more specific thanprotamine sulfate

50% solution ethanol will polymerizeany fibrin monomers resulting to gel

formation


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Fibrinogen Levels

Quantitated by various methods includingprecipitation, denaturation, turbidimetry or

fibrin clot density method, coagulableproteins assays, immunological assays and

modified thrombin time. NV: 200-400 mg/dL

Decrease in liver disease or consumption offibrinogen owing to accelerating

intravascular clotting. Fibrinogen titer may be useful:

Normal = 1:128 to 1:256

Abnormal =


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Latex FDP Assay

Latex particles are coated with antibodies toFSPs.

If significant level of the fragments are in theserum, agglutination will occur.

DIC

Pulmonary embolism

DVT (Deep vein Thrombosis)

Myocardial infarctionPre-eclampsia


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Latex D-dimer Assay:

Measures specific cross-linked D-dimerfragments from degradation of stabilizedfibrin clots by plasmin.

D-dimers are evidence of intravascularfibrin formation.

Monoclonal antibodies to D-dimers areattached to latex particles causing

agglutination if D-dimers are present Specimen of choice: fresh citrated blood

Useful in the diagnosis of DIC

NV:


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Plasminogen Assay:

Chromogenic or fluorogenic substrateallow functional quantitation ofplasminogen.


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Fibrinopeptides A or B Assay:

Fibrinogen fragments can bemeasured by radio-immunoassay.


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Protein C (PC) and Protein – S

(PS) and AT III assaysCan all be measured for a degree of

activity with chromogenic assays or

with immunoassays to measure theconcentration of the molecule (i.eantigen).


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Activated Protein C Resistance

(APCR) Is the inability of APC to prolong

clotting tests when added to the APTT.

This phenomenon is characteristic of agenetic thrombotic disorder known asfactor V Leiden.

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10. Laboratory Evaluation of Fibrinolysis